The installer used for the kf5 ISOs being tested is UEFI ready.
Calamares does not have UEFI support yet, not sure how soon that is planned.
No need to look at another distro to follow calamares, it is build for KaOS about every 2-3 days, updates are posted:
But first needed is getting the ISO creation UEFI ready, I need to rebuild a system here for that first, since there is no way for me to proceed any further with this, until I have UEFI ready hardware.